1. Technical Field
The present invention relates to a waterproof plug used for an electric connector to prevent water from entering into a connector housing through a space between a wire connected to a terminal and a connector housing.
2. Description of the Related Art
An example of related art waterproof plug used for a connector is disclosed in Japanese Published Unexamined Utility Model Application No. 62-163879.
A related art waterproof plug formed of rubber has a cylindrical body portion with a wire insertion hole. Further, the waterproof plug is formed with an inner corrugated sealing portion brought into tight contact with the outer circumference of a wire and an outer corrugated sealing portion brought into tight contact with the inner circumference of a terminal insertion cavity of a connector housing. Further, the waterproof plug is formed with a cylindrical clamped portion on the front side of the body portion in such a way that a clamping recessed portion is formed on the outer circumference of the clamped portion. Furthermore, a tapered portion is formed at the inner rear end circumference of the body portion for facilitating the insertion of the wire into the waterproof plug.
To use this waterproof plug, the waterproof plug is first fitted to the outer circumference of the wire coating material of the wire and then pushed into the rear end of the terminal (to which an end of a conductor of the wire has been clamped). Further, a clamping piece of the terminal is clamped against the recessed portion of the waterproof plug to fix the waterproof plug to the terminal. Under these conditions, the terminal is inserted into the terminal insertion cavity of the connector housing. Therefore, it is possible to fit the terminal into the connector housing under waterproof conditions.
In the related art waterproof plug as described above, however, whenever the wire is moved or pulled in radial detections, since the waterproof plug is easily deformed radially outward by the wire, there exists a problem in that the sealing characteristics deteriorate both at the sealing portion between the waterproof plug and the wire and at the sealing portion between the waterproof plug and the connector housing. To improve the sealing characteristics, when the diameter of the wire insertion hole of the waterproof plug is reduced, there arises another problem in that the wire cannot be inserted into the waterproof plug easily.